This is the "rock polisher" thesis of life, which I've also called the "bully thesis." I grew up swapping between different parts of America that approached "how to generate a functional adult" differentally. Some places, it was "love and care for your fellow man. Work together to make a better world." Other places it was "we believe the world is harsh and unforgiving, therefore we're gonna beat you to get you ready for it."
What I've learned is that society is exactly how you make it. If you allow kids to bully and beat the shit out of each other in the playground, you're gonna get a society of Biggest Fist Wins. If you go the other direction, you'll get one where people work together and work to see the best in each other.
Once you've been raised one way though, the other way seems a weakness, so I generally don't have hope of doing anything other than preach to the choir.
In your example - what's the point of thicker skin if people simply don't say mean things to each other?